El
Niño - a warming of the ocean current along the coasts
of Peru and Ecuador that is generally associated with dramatic changes
in the weather patterns of the region; a major El Niño event generally
occurs every 3 to 7 years and is associated with changes in the weather
patterns worldwide

Entropy
- the amount of Energy that is not available
for work during a certain process

Equation
of State - the state of an ideal gas can be shown to be pa=RT,
where p is the pressure; a is the specific
volume; R is the specific gas constant;
and T is the absolute temperature

Equilibrium
- a state of balance in a system where opposing forces or fluxes
balance

Equilibrium
Level (or EL) - on a sounding,
the level above the level of free convection (LFC) at which the temperature
of a rising air parcel again equals the
temperature of the environment. The height of the EL is the height at
which thunderstorm updrafts no longer accelerate
upward. Thus, to a close approximation, it represents the height of expected
(or ongoing) thunderstorm tops.

Evapotranspiration
- loss of water from the soil both by evaporation
and by transpiration from the plants
growing thereon

Exosphere
- the upper most layer of the earth's atmosphere; the only
layer where atmospheric gases can escape into outer space

Extratropical
Cyclone - a cyclone in the middle
and high latitudes often being 2000 kilometers in diameter and usually
containing a cold front that extends toward
the equator for hundreds of kilometers